not the 40 passengers and crew who were murdered by them on Flight 93 on 9/11. The Memorial, being set up by the National Park Service, is full of Islamic symbolism. As the memorial is now, it will be a symbol of the triumph of Islamic extremists over Americans.
The controversy is discussed in Wikipedia.
In addition, Tom Burnett Sr., whose son (Tom Burnett) died in the crash, said he made an impassioned speech to his fellow jurors about what he felt the crescent represented. “I explained this goes back centuries as an old-time Islamic symbol,” Burnett said. “I told them we’d be a laughing stock if we did this.” 
This design choice initially created controversy because the terrorists who hijacked the aircraft were Muslim and conducted the attacks in the name of Islam. The crescent is generally recognized as an Islamic symbol and the Red Crescent is used as the Islamic equivalent of the Red Cross. The crescent is also represented on a number of flags of countries with Muslim majorities, including Pakistan.
The winning design’s crescent is also oriented toward Mecca. While the Belmont Club’s Richard Fernandez noted that this may just be a coincidence he went on to note: “But what a coincidence! Memorials are symbols above all and it may be inappropriate to commemorate Flight 93 with a Red Crescent facing Mecca.” 
The architect asserts that this is coincidental and there is no intent on referencing Muslim symbols. This sentiment has been shared by several victims families as well, such as the family of Ed Felt. Representative Tom Tancredo of Colorado has opposed the design’s shape “because of the crescent’s prominent use as a symbol in Islam.” The Council on American-Islamic Relations has denounced criticism as Islamophobic. 
James Lileks, a journalist and architectural commentator, noted in regard to the winning design: “We don’t need giant statues of the guys ramming the drink cart into the door. But pedantic though such a monument might be, future generations would infer the plot. All you get from a Crescent of Embrace is a sorrowful sigh of all-encompassing grief and absolution, as if the lives of all who died on that spot were equal in tragedy. They were not.” 
Mike Rosen of the Rocky Mountain News wrote: “On the anniversaries of 9/11, it’s not hard to visualize al-Qaeda celebrating the crescent of maple trees, turning red in the fall, “embracing” the Flight 93 crash site. To them, it would be a memorial to their fallen martyrs. Why invite that? Just come up with a different design that eliminates the double meaning and the dispute.” 
Don’t you just love the Islamaphobic comment? If someone doesn’t like something, they’re “afraid” of you and hate you. (When did phobia become hate?) I don’t hate Muslims. I do hate what has been done by Muslims in the name of Allah to Americans and Christians and other non-Muslims around the world. I don’t see any reason to use their symbols in our memorial to our people. And I see many reasons not to do so.
To register a complaint about the subject, call the National Park Service at (814) 443-4557 or fax them at (814) 443-2180. They can also be emailed.